Propeller



Feb. 7, 1939. A. BERLINER PROPELLERv Filed March 7, 1936l 2 Sheets-Sheet l INVENTOR.

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` Feb, 7, 1.939. H, A. BERLINER y 12,146,367

PROPELLER Filed March '7, 1936 2 Sheets-Sheet 2 INVENTOR.

ATTORNEYS HE NRV A, B RL/NER Patented Feb. 7, 191,39

'PATENT loi-FICE PROPELLER.

Henry A. Berliner,

by menne assignments, search ration of Maryland Washington, D. C., assihioi';

to Engineering and Ite- Corporation,U Riverdale, Md., a corpo- Application Maren 7, 1936, serial. No. 61,587

iclaims. (ci. 17o-16s) `This inventionrelates to propellers and more particularly to propellers in which the blades are separately mounted in a hub.

3 In propellers having separately mounted blades, and particularly in winch the blades are adjustable during flight, it is necessary either to provide` largev heavy bearings to carry the centrifugal loads .-1 on the blades or to provide some other means to vhold the blades in the hub sockets. If the blades are interconnected ,or are connected `tov the hub by means other than: bearings, difficulty is encountered in providing for sufficient turning of the blades to give the desired range of pitch adjustment without causundesirable movement of the blades. 1t is accordingly one of the objects of the invention to provide a propeller having separately mounted blades in which the necessity for thrust bearings is eliminated and the blades can be turned through a large angle. i

Another object of the invention ist'o provide a propeller in which the radial position of the blades can be varied to balance the propeller.

In one desirable arrangement the blades are connected to the hub or to each other by means of tubular tensionmembers provided with a series of axial slots to form an annular series of spaced tension elements. I have found that by using a tube of minimum diameter consistent with the requisite strength, whereby-the tension elements will lie relatively close to the axis of rotation, the blades may betwisted through a lange angle Without producin any appreciable ra al movement thereof. By 4screw threading the tension member or members to the blades or to fastening means in the hubV and by providing a mechanism for turning the tension member or the fastening means, a very simple adjustment for shifting the blades to balance the propeller is provided. The tension members may also be set to urge the blade toward its normal flight position, thereby partially or wholly balancing the centrifugal torsional force on the blade.

Other objects, advantages and novel features of the invention will be apparent from the following description when read in connection with the accompanying drawings, in which:

Figure 1 is a central section of a propeller embodying the invention; A

Figure 2 is a section with parts in elevation on the line III--II of Figure 1;

, Figure 1; and

Figure 3 is a section on the line III-III of Figure 4 is a partial central section of another embodiment of the invention.

As 'shown in Figures 1 to 3, the propeller com: prises a lhub 5 having a pair of oppositely facing radial ysockets 6 adapted to carry the blades. l

The hub 5 is adapted to be drivably connected to an engine shaft or to a suitable extension of an engine shaft and has splined to its outside a sleeve 1 formed on its outer surface with a pair of cam slots. The sleeve 1 is connected through a bearing 8`with a collar 9 which is slidably mounted on aplurality of stationary rods II so as to be 4axially inovable but not rotatable.

The collar 9 carries a plurality of radial pins I2 slidable in slots I3 in a collar I4 which is rotatably mounted in a xed extension I5 which may be mounted on the engineer other part of the craft with which the propeller is used. A lever I6 extends through a suitable slot in the extension I5 'and is adapted to be moved manually or through any suitable power mechanism to change the pitch of the blades,'as will appear later.

A pair of blades are mounted in the sockets 6, the blades as shown being formed in the manner more particularly described and claimed in my copending application Serial No. 67,588, filed March 7, 1936, with metal' spuds I1 having molded blades I8 of Micarta" or the like formed therein. The spuds I1 havecylindrical root portions journaled inthe sockets 6 through suitable bearings I9 and have reinforcing portions extending into ancl` forming an intimate bondF with the molded portions I8.

The angular position of the spuds -and consequently of the blades is controlled by the mechanism described above through sleeves 2| journaled in the sockets 6 and secured?, to the root ends of the blades as by means of intermeshing teeth shown at 22. Rods 23 extend through suitableslots in the sockets 6 and are secured to the sleeves 2|, the free ends of the rods carrying pins which are slidable in the cam slots in the sleeve 1. I i

To adjust the angular position or pitch of the blades, the lever I6 may be moved to rotate the sleeve I4. Due to the pin and slot connection I2, I3 this will shift the collar 9 and sleeve 1 axially, causing the ends of rods 23 to move in the cam slots in sleeve 1 and turning the sleeves 2| and the blades about their own axes in the sockets 6. While the particular mechanism shown for changing the pitch of the blades has been described in some detail, it will be apparent ,-"that any 'other suitable type of pitch changing mechanism might 'be employed.

In order to hold the blades in then-sockets,

series of tension strips 28 arranged lvin annular array about the axis of rotation of the blades. Preferably the tube has the minimum diameter consistent with strength so thatl the strips 20 lie closely adjacent the 'blade axis. I have found 'that with this arrangement the blades may be twisted through a large angle without producing any appreciable shortening of the tension member and consequently without causing appreciable shifting of the blades axially of their sockets.

The enlarged center portion 26 of the tension member is held in place and centered in the hub by means of blocks 23 secured in the hub in any suitable manner and .gripping the ends ofv the portion 26. Preferably the portion 26 is formed as a worm gear: meshing with a worm 3| which is rotatably mounted in the hub and whose shaft extends through the hub se that itmay be engaged by any suitable tool and turnedi I'he portions 25 of the tension member are formed with threads of the same hand so that turning the tension member will move one of the blades radially inwardly and the other outwardly, thereby permitting the propeller to be balanced easily and quickly after it is assembled. This is an impor- .tant feature since it enables a great saving in time and effort over the present methods of balancing propellers.

' In the use of adjustable pitch propellers on aircraft, it is desirable tobe able to turn the blades to a 90 pitch angle in order to feather the blades and at the same time to turn them to a reverse angle for braking during landing. For example, a plane with four engines, when not heavily loaded, may desire to run on two engines to ei'ect a saving in fuel and the two idle propellers should be turned with their blades substantially parallel to redce air resistance.;V When this condition is coupled with reversibility of the blades for braking, it means that the blades must turning through a total angle in the neighborhood of 110.

Angles of this, or even of greater magnitude, are possible with the present invention, it being appreciated that the tension member can be set at approximately the center of the total arc of twist so that it must be turned or twisted only half of the total angle, or about 55 in each direction. When the tension member is so set, its natural resiliency tends to turn the blade toward or even past its normal setting for forward night, the tension member under the conditions assumed above tending to turn the blade to a forward pitch angle of 35. This effect is increased by the pull on the tension member due to the centrifugal force on the blades so that a very appreciable turning moment is exerted by the tension member tending wholly or partially to balance the centrifugal torsional eifect on the blades tending to turn them into their plane of rotation. In order to transmit this torsional force between the tension member and the blades, the ilt of the portions 25 may be made very tight or suitable set screws may be provided to lock the blades and the tension member against undesired relative rotation.

ligure 4 illustrates a three blade propeller embe capable of bodying the invention and for the sake of brevity of description parts therein corresponding to like partsI in Figures 1 to 3 have been designated by the same reference numbers plus 100. In this construction a separate tensionA member |24 is provided for each blade and the inner ends of the tension members extend through blocks 2l which are rigidly secured in the sockets |06 and which have nuts |30 screw threaded on the ends thereof. The nuts |30 are formed as worm gears and mesh with worms |3| rotatably mounted in the hub by means of which the blades can be adjusted separately to balance the propeller. It will be apparent that instead of turning the nuts |30 on the tension members, the entire tension members` might be turned to effect the adiustment by means of the screw threads at |25.

- While only two embodiments of the invention have been shown and described, it will be apparent that many -changes might be made or that other embodiments might bev devised. Itis acccrdingly not intended to limit the scope of the invention to the forms shown or otherwise than' by the terms of the appended claims.

'1. A propeller comprisinga hubhaving a pair of oppositely facing sockets, a blade rotatably mounted' in each of s aid sockets, means for adjusting the angular positions vof the blades, and means for holding the blades in the sockets including a tubular member secured to the root ends of the blades substantially at the axis of rotation thereof and formed with a plurality of axial slots to provide an annular series of spaced tension members, means to center the tubular member in the hub, and means operable from outside of the hub to adjust the position of the'blades relatively to the tension member thereby to' balance the blades.

2. A propeller comprising a hub having a pair of oppositely facing sockets, a blade rotatably mounted in each of said sockets, means for adjusting the angular positions of the blades, and means for holding .the blades in the sockets including a tubular member screw threaded to the root ends of the blades substantially at the axis of rotation thereof and formed with a plurality of axial slots, means to center the tubular member in the hub, and'means to turn the tubular member thereby to adjust the axial positions of the blades in the hub.

43. A propeller comprising a hub having a pair of oppositely facing sockets, a blade rotatably mounted in each of said sockets, means for adjusting the angular positions of thegblades, and means for holding the blades in the sockets including a tubular member screw threaded at its opposite ends into the root ends of the blades and having its center portion formed to engage oppositely facing thrust bearings in the hub to center said member. said member being formed with series of axial slots between its center portion and its opposite ends, and means to rotate said member to adjust the positions of the blades in their sockets.

4. A propeller comprising a hub having a plurality of radial sockets, blades mounted in said sockets, and means for holding each blade in its socket comprising a tension member in the hub secured to the root end of the blade, a nut in the socket screw threaded to the tension member to hold it in the socket, and means operable from outside the hub to turn said nut thereby to adjust the position of the blade in its socket.

HENRY A. BERLINER. 

